Variable feed for stokers



May 22, 1928.

c. J. PARKER VARIABLE FEED FOR STOKERS Filed May 16, 1927 I 3 Sheets-Sheet 1 mw/E- VT C iwaz 4 TUR/VE May 22, 1928, 1 c. J. PARKER VARIABLE FEED FOR STOKERS Filed May 16, 1927 s Sheets-Shet 2 gv-nzyF /ve-v c. J. PARKER VARIABLE FEED FOR STQKERS May 22, 1928. 1

Filed May 16, 1927 5 Sheets-Sheet 1 uvMav 7-0 Patented May 22, 1928.

CYRUS J. PARKER, OF'PORTLAND, OREGON.

VARIABLE FEED FOR STOKERS.

Application filed Kay 16, 1927. Serial No. 191,807.

This invention relates generally to coal burning furnaces, and particularly to the under feed type of stoker in which coal is fed up to the fire by means of a worm.

5 The first object of this invention is to provide an exceedingly efficient and smooth operating variable speed mechanism whereby the amount of rotation applied to a feed screw can be varied at will while the speed 10 of the prime mover remains constant.

The second object is to provide a pawl and ratchet mechanism in which the pawl is backed away slightly from the tooth before being withdrawn from same.

These, and other objects, will become more apparent from the specification following as illustrated in the accompanying drawings, in which:

Figure 1 is a front elevation of the variable speed mechanism of which Figure 2 is a vertical section taken along the line 2-2 in Figure 1. Figure 3 is a front elevation of the device with the cover plate removed.

Figure 4 is a vertical section taken along 25 the line 44 in Figure 2. Figure 5 is a dia rammatic view showing the first portion of the pawl travel just as it is approaching its stop. Figure 6 is a similar view showing the pawl just about to engage its stop. Fig- 30 ure 7 is a similar View showing the pawl being held into engagement with a tooth in the ratchet. Figure 8 is a similar view showing the pawl at the end of its working stroke.

Figure 9 is a similar view showing the pawl backed off slightly before it is withdrawn from the tooth. Figure 10 is a similar view showing the pawl completely withdrawn from the tooth and with the ratchet slightly backed away from the position to which it was driven.

Similar numbers of reference refer to similar'parts throughout the several views.

No attempt is made to show the drive motor or worm screw, but only those parts which are intimately connected with this invention.

Referring in detail to the drawings, the shaft 11 is provided with a square end 12 which is connected by means of a suitable cable (not shown) to a worm screwby means of which coal can be fed to a fire. The end 13 of the shaft 11 is also square to permit manual operation, if desired. The shaft 11 journals in a bushing '14 at one end and is pinned to a hub 15 of a ratchet wheel 16 at its opposite end by means of a pm 17.

The bushing 14 passes through the casing 18 and has mounted thereon a worm wheel 19 on whose eccentric hub 20 is rotatably mounted a .crank 21 to whose hub 22 is secured an external gear or pinion 23 by means of the key 24.

Within the casing 18 is mounted a stationary internal gear 25 which meshes with the gear 23 at all times. The gear 25 is held in osition by means of the screws 26.

n the crank 21 is mounted a pawl 27 which swings on the shouldered screw 28 which rides against the inside 30 of the casing 18. The point 31 of. the pawl 27 can engage the teeth 32 of the ratchet wheel 16 only when the roller 29 rides against one of the faces 33, 34 or 35 of the disk 36, which is held in one of four positions on the shaft 37 by means of a pin 38 which is mounted in the casing wall 39.

The shaft 37 is slidably mounted in its bearings and has a shouldered end 40 within a counterbored portion 41 of the casing 18, which counterbore also contains a spring 42 whose function it is to urge the shaft 37 with its disk 36 toward the pin 38. A knob 43 is provided for the manual setting of the disk 36.

The face 44 of the disk 36 corresponds practically with the curved surface 30 so that when the disk 36 is turned with the face 44 lowermost there is no engagement between the pawl point 31 and the ratchet teeth 32. A spring 45 is provided for the pawl 27 to urge the roller end of the pawl upward, that is with its point 31 out of engagement with the teeth 32. i

Owing to the fact that the screw 28 is eccentrically mounted with relation to an eccentric it describes apath indicated by means of the dotted line 46.

A cover plate 47 is placed over the front of the casing 18 and held in position by meansof the bolts 48. The knob 43 is preferably provided with characters 49 which indicate whether the screw is being moved one, two or three ratchet teeth at an operation or whether it is not being moved at all. An arrow 50 points to the character corresponding with the faces 33, 34, 35 or 44 as the case may be.

Rotation is supplied to the worm wheel 19 by means of the worm 51 on the shaft 52 provided at one end with a coupling 53 for connection to a motor (not shown) and at its other end with a spider frame 54 through which may be attached to the frame 54;

It can be seen by this construction that the feed screw may be stopped entirely .or it may be fed intermittently through one, two or three ratchet teeth at the will of the operator without changing the motor speed, and at the same time so driving the screw that the 'most favorable conditions for the drive are at the start of the operation, which is the moment when the inertia of the coal feed screw must be overcome.

It is found in practice with various types of feed mechanisms that when a coal-feeding screw is fed a definite distance by intermittent movements that there is a slight tendency for the screw to back up a trifle at the end of each movement. In order to avoid the difliculty of disengaging the teeth of the ratchet and pawl advantage is taken of the fact that, owing to the peculiar motion of the pawl point 31, a slight excess movement is provided from which the point 31 backs away .providing easy clearance for the point 31.

distances through which the feed operates,

as well as various ratios of feed, can be employed without departing from the spiri of this invention.

I claim:

1. A variable feed for stokers having, in combination, a stationary internal gear; an eccent-rically mounted pinion meshing with said gear; a crank actuated by said pinion; a pawl mounted on said crank; a ratchet concentric with said internal gear; a shaft driven by said ratchet; and cam means for moving said pawl into momentary engagement with said ratchet.

2. A variable feed for stokers having, in combination, a stationary internal gear; a driven shaft concentric with said gear; a pinion eccentrically mounted on said shaft meshing with said gear; a crank carried by me nt with said ratchet; a multiple lobed stationary cam adapted to have one of its faces moved into the path of said pawl whereby said pawl is momentarily moved into engagement with said ratchet wheel; and means for rotating said pinion.

3. A variable feed for stokers having, in combination, a planetary pinion; an internal gear meshing with same; a shaft concentric with said internal gear; a crank carried by said pinion; a ratchet wheel concentric with said internal gear ;a crank pin on said crank describing a hypotrochoid; a pawl mounted on said pin; a concentric casing around said ratchet wheel; a spring urging said pawl out of engagement with said ratchet wheel and against said casing; and reduction gears for rotating said pinion.

4. A variable feed for stokers having, in combination, a somewhat cylindrical casing open at one side and having a removable.

cover therefor; a ratchet wheel having a hub journaling in said cover; a driven shaft secured to said ratchet wheel and journaling in said casing; sa1d shaft having an eccentric hub thereon;

a planetary pinion and crank secured together and. journaling on said eccentric hub;

' an internal gear around said pinion and meshing therewith; a pawl pivotally mounted on said crank having a spring urging same outwardly out of engagement with said ratchet; a transverse shaft journaling in said casing; a worm on said transverse shaft meshing with said worm wheel; a multiple lobed cam having lobes of various lengths adapted to urge said pawl momentarily into engagement with said ratchet wheel for various lengths of time; and means for positioning said cam and changeably holding same in a fixed position. I

CYRUS J. PARKER.

a worm wheel journaling on 

